1. Field of the Invention
The present invention relates to a multi-band antenna and a mobile communication terminal having the same, and more particularly, to an antenna in which a plurality of slots are formed to ensure multi-band characteristics and a mobile communication terminal in which a matching ground surface is formed to be capacitively coupled to the antenna to achieve broadband characteristics.
2. Description of the Related Art
Drastic development in mobile telecommunication technology has reduced size of and diversified functions of mobile communication devices. In line with the compact trend of portable terminals, internal antennas have been introduced. Also, with diversified mobile services, efforts are underway to develop an antenna covering various frequency bands which are currently available.
The internal antenna is installed inside a terminal, thereby entailing several problems. That is, the small internal antenna mounted inside the terminal experiences decrease in gain, and its proximity to internal devices affects antenna characteristics due to the surrounding metal materials. Moreover, mobile phones with diverse functions may be altered in antenna characteristics by cameras, liquid crystal panels (LCDs) and batteries. Therefore, the antenna needs to have high gain and broadband frequency so as not to be changed in characteristics despite effects from the surrounding devices.
FIG. 1 is a perspective view illustrating a conventional planar inverted F-type antenna (PIFA).
Referring to FIG. 1, a radiator 101 is disposed on a ground surface 100 and a short-circuit plate 102 is bent perpendicularly from an edge of the radiator 101 to be in contact with the ground surface 100. A feeding point 103 is located to allow for impedance matching of the antenna.
The planar inverted F-type antenna is construed to be a kind of a short-circuit microstrip antenna, in which the short-circuit plate 102 is formed between the ground surface 100 having an electric field of zero and the radiator 101 so that the radiator 101 is halved in length. Here, the radiator 101 having a width smaller than a width of the short-circuit plate 102 increases effective inductance of the antenna device, and reduces a resonant frequency over a general short-circuit microstrip antenna having a radiator with an identical length. This allows the short-circuit microstrip antenna to be further reduced in length while maintaining the PIFA structure.
The conventional PIFA exhibits dual band characteristics but is configured to have an edge bent, thereby degraded in gain and efficiency.